Combustion apparatus

ABSTRACT

A combustion apparatus is disclosed having a closure member disposed about a fuel nozzle and formed with a plurality of radially elongated and mutually spaced slots for delivery of air into a combustion chamber as a plurality of discrete streams about and generally along the fuel spray axis so as to mix the air and fuel in a manner producing low smoke combustion.

Unite States Patent [72] Inventors Milton J. Kenworthy;

Clifford C. Gleason; Michael M. Bluestone,

all of Cincinnati, Ohio [21] Appl. No. 796,391 (22] Filed Feb. 4, 1969[45] Patented June 29, 1971 [73] Assignee General Electric Company [54]COMBUSTION APPARATUS 2 Claims, 5 Drawing Figs.

[52] U.S.Cl 60/3937, (JO/39.65,60/39.74,431/352 [56] References CitedUNITED STATES PATENTS 3,031,012 4/1962 Brola 431/183 2,398,654 4/1946Lubbock et al 60/3965 2,560,223 7/1951 Hanzalek 60/3965 3,283,50211/1966 Lefebvre 60/3974 3,447,317 6/1969 Dakin 431/183X FORElGN PATENTS894,470 4/1962 Great Britain 60/3974 464,055 8/1928 Germany 431/183Primary Examiner-Carroll B. Dority, Jr. Attorneys-Derek P. Lawrence,Erwin .F. Berrier, Jr, Lee

Sachs, Oscar B. Waddell and Frank L. Neuhauser ABSTRACT: A combustionapparatus is disclosed having a closure member disposed about a fuelnozzle and formed with a plurality of radially elongated and mutuallyspaced slots for delivery of air into a combustion chamber as aplurality of discrete streams about and generally along the fuel sprayaxis so as to mix the air and fuel in a manner producing low smokecombustion.

PATENTEnJuwzslan 3.589127,

SHEET 1 UP 2 42 INVENTORS.

1+ MILTON J. muwonruv CLIFFORD C. GLEASON MmHAEL M. ewesmms Whilenumerous combustion chamber structures and combustion chamber airbaffling means have been proposed heretofore, such proposals havegenerally been concerned with enhancing thermodynamic combustionefficiency, controlling temperature variations within the combustionchamber, or eliminating hot spots or streaks on the liner or chamberwall which might result in premature burnout. Furthermore, such priorstructures tend to be highly configuration dependent. That is, theircharacteristics, particularly smoke level, tend to vary widely with thetemperature, pressure and flow rate of the air supplied to supportcombustion, the fuel spray angle and delivery pressure, and the locationof dilution and cooling holes.

A primary object of this invention is to provide means for deliveringair into-a combustion chamber and mixing said air with the fuel in amanner which results in efficient and low smoke combustion of the fuel.

Another object of this invention is to provide a combustion apparatuswherein low smoke combustion may be achieved over a wide range of airand fuel delivery conditions.

The above and other objects are achieved by the present invention byproviding means for delivering air into the combustion chamber as aplurality of discrete streams about the fuel spray which are directiongenerally with the fuel spray. In this manner, low-pressure wake regionsare established between adjacent airstreams followed by a region ofinteraction and turbulent dissipation of the discrete streams wherebymixing of the combustion air and fuel is promoted in a manner producinglow smoke combustion.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter of this invention, it isbelieved the invention will be better understood from the followingdescription of the preferred embodiment when taken in connection it theaccompanying drawings wherein:

FIG. I is an axial cross-sectional view of an exemplary gas turbinecombustion apparatus embodying the present invention, said view takenalong lines ll of FIG. 2;

FIG. 2 is a partial cross-sectional view taken along lines 2-2 of FIG. 1and drawn to an enlarged scale;

FIG. 3 is a partial cross-Sectional view taken along lines 33 of FIG. 2and drawn to an enlarged scale, said view diagrammatically showing themanner in which a portion of the air is delivered into the combustionapparatus of FIG. 1;

FIG. 4 is a partial cross section view drawn to an enlarged scale andshowing the fuel delivery portion of a prior art combustion apparatus;and

FIG. 5 is a graph depicting the smoke levels obtained at various airtemperatures for the combustion apparatus of this invention and theprior art combustion apparatus of FIG. 4.

Referring now to the drawings and particularly to FIG. 1, a continuousburning combustion apparatus of the type suitable for use in a gasturbine engine has been shown generally at as comprising a hollow body12 defining a combustion chamber 14 therein. The hollow body 12 isformed with a domed end 16 and, as shown in H6. 2, is generally annular.It should be understood, howe but this invention is not limited to suchan annular conngi -uon and may be employed with equal effectiveness incombustion apparatus of the wellknown cylindrical can or cannular type.

The domed end 16 of the hollow body I2 is formed with a plurality ofspaced openings I8, each respectively communicating with a suitableconduit 20 adapt to deliver at least a portion of the air required toburn the fuel and dilute the gaseous products of combustion into thechamber 147 The conduit 20 is secured to the hollow body 12 at 22 as bywelding or other suitable means and extends upstream of the opening 22where it terminates in a radial flange 24.

The hollow body 12 may be formed with a plurality of cooling airpassages 26 adapted to deliver a protective boundary layer of coolingair along the inner wall surfaces of the hollow body and a plurality ofdilution holes 28 for delivery of the remaining portion of the requiredcombustion air. As used herein, the term combus ion air" includes boththe air required chemically to completely burn the fuel or forstoichiometric combustion plus any excess or dilution air which may berequired to effect combustion and lower the temperature of the gaseousproducts of combustion to a temperature sufficiently low to enable theireffective use, for example, in driving turbomachinery.

The hollow body 12 may be enclosed by a suitable shell 30 having anupstream end passage 32 communicating with a source of compressed air,as for example the discharge end of a gas turbine engine compressor.

An annular snout assembly 34 may be employed to direct the compressedair from passage 32 to the opening 18, the cooling air passages 26 andthe dilution air passages 28. As best shown in FIG. I, the snoutassembly 34 is secured to the hollow body 12 and extends upstreamthereof, defining a chamber 36 upstream the hollow body domed end 16 anda passage 38 for delivery of the compressed air to the chamber 36.

The outer shell 30 is sized in relation to the snout assembly 34 andhollow body l2 so as to define annular passages 40 and 42 therebetweenwhich function in part, to deliver compressed air from passage 32 tocooling air passages 26 and dilution air passages 28.

A fuel nozzle assembly 44 having a discharge end 46 adapted to deliverat least one generally conical spray of fuel (indicated generally at 48)about axis 49 is provided for each hollow body opening 18. Each nozzle44 is secured to the shell 30 as at 50 and extends inwardly through theouter shell 30 and snout assembly 34 and terminates at discharge end 46.The nozzle discharge end 46 may include a shroud of the wellknown typeand is formed with a suitable external surface 52 which is preferablycylindrical.

Means for directing at least a portion of the combustion air into thechamber 14 about the nozzle discharge end 46 has been shown at 54 ascomprising a closure member 56 which extends between the nozzledischarge end 46 and the conduit 20.

The closure member 56, as best shown in FIGS. 2 and 3, is formed with aplurality of spaced, elongated slots are respectively defined, in part,be generally parallel sidewalls 58 which extend generally radially withrespect to the fuel spray axis 49.

As has been diagrammatically shown in FIG. 3, the slots 58 aresufficiently spaced relative to one another and have sufficient axiallength X" so that the combustion air passing therethrough enters thechamber 14 as a plurality of discrete streams of air 60. By spacing thestreams 60, low-pressure wake regions 62 are established intermediateadjacent streams due to the aspirator effect of the discrete streams.Downstream of the closure member 56, as diagrammatically shown at 64,the discrete streams 60 interact and dissipate in a region of highturbulence. In addition to the above, the slots 58 are preferably sizedin relation to the cooling passages 26 and the dilution passages 28 sothat the amount of air delivered to the chamber 14 by each means 54 is asubstantial portion of the air required for stoichiometric combustion ofthe fuel delivered by its respective nozzle 44. For example,satisfactory results from the standpoint of smoke in the gaseousproducts of combustion have been obtained with the slots 58 sized todeliver from 25 percent to percent of the air required forstoichiometric combustion of the fuel. In opera tion, the low pressurewithin the regions 62 operates to pull minute fuel droplets from thefuel spray 48 into that region for initial mixing with the air. Finalmixing of the air and fuel then occurs in the region 64 of turbulentinteraction and dissipation of the airstreams. By introducing air inthis manner about the fuel "spray, it has been found that thoroughmixing of the air and fuel is accomplished and the occurrence of localoverrich pockets of fuel is greatly reduced with the result that lowsmoke combustion is achieved.

For comparison purposes, the nozzle portion of an exemplary prior artcombustion apparatus has been shown in FIG. 4 wherein air is introducedabout the fuel spray 48 in a swirl pattern by vanes 66. A comparison ofthe smoke level in the gaseous products of combustion of the prior artstructure of HG. 4 and the apparatus of this invention has beengraphically shown in FIG. as a function of the temperature of the air inpassage 32. it will be noted that markedly lower smoke levels wereobserved in the combustion apparatus of this invention than wereobserved for the prior art structure of FlG. 4. it will also be notedthat the apparatus of this invention exhibited less sensitivity tochanges in the air temperature. Although smoke levels will vary withfactors such as the overall fuel-to-air ratio, the included angle of thefuel spray cone 48, the fuel delivery pressure and the pressure of theair, it has been found that the combustion apparatus of this inventionexhibits relatively low sensitivity insofar as smoke level output isconcerned to variations in these parameters.

Referring again to FIGS. 1 and 3, the axial extent of slots 58 may beformed at an angle relative to the fuel spray axis 49 so as to impart aswirling or spiral motion to the air to minimize the occurrence of hotspots or streaks along the inner surface of the hollow body 12.Additionally, to promote a sweeping action of the air over the nozzledischarge end 46 to prevent carbon accumulations thereon, the slots 58may be formed so as to direct the streams of air 60 with a slightradially inwardly component relative to the fuel spray axis 49. It hasbeen found also that lower smoke content in the products of combustionis achieved when the slots 58 or discrete airstreams 60 are closelyspaced relative to the fuel spray axis 49, as is shown in FIG. 1, andsuch is the preferable form. By so locating or forming the slots 58, thediscrete streams 60 intersect the fuel cone 48 upstream of the turbulentinteraction and dissipation region 64 which is believed to enhance thefuel-air mixing action.

As has been shown in FIG. 1, the nozzle discharge end 46 and theair-directing means 54 are preferably spaced upstream of the chamberopening 18 so that the region of turbulent interaetion and dissipation64 of the discrete streams 60 is initiated within the conduit 20.

The closure member 56 may include an upstream portion 66 having a bellmouth or outwardly flared upstream end 68 and adapted to define anannular passage 70 intermediate the chamber 36 and the slots 58 toefficiently direct air in a generally streamline manner from the chamber36 to the slots 58.

With reference now to FIGS. 1 and 2, the closure member 56 is preferablysecured to conduit in a manner permitting relative movement between thenozzle 44, the closure member 56 and the conduit 20 during periods ofrelative thermal expansion and contraction. To this end, the closuremember 56 may include a peripheral flange 72 which is housed and floatswithin a peripheral groove 74 cooperatively formed by a retaining ring'76 and the conduit flange 24. Rotation ofthe closure member 56 relativeto the nozzle 46 and the conduit 20 may be prevented by providing cars80 which extend outwardly from the flange 74 through slots 82 formed inthe retaining ring 76.

As shown in FIG. 1, the closure member 56 may include a centrallydisposed wear sleeve or collar 84 formed with a centralopening 86 sizedto slidingly receive the external surface 52 of the nozzle discharge end46 in close fitting relationship. The wear sleeve 84 may extend upstreamof the slots 58 so as to define the inner boundry of passage 70 and maybe outwardly flared as at 88 to facilitate insertion of the nozzle intoopening 86.

Although the closure member 56 has been show disposed at the upstreamend of the conduit 20, it should be understood that it may be disposedintermediate the ends of the conduit, the conduit may be eliminated andthe closure member 56 disposed at the hollow body upstream end opening18, or the air-directing means 56 may be integrally with the hollow bodyl2.

Although the present invention has been depicted and described inconnection with a combustion apparatus of the annular-type, it will beappreciated by those skilled in the art that this invention may beemployed with equal effectiveness in other combustor configurations suchas the well-known cannular or cylindrical can-type. Further, althoughone embodiment of the invention has been depicted and described, it willbe appreciated that many additions, modifications and changes may bemade thereto without departing from the inventions fundamental theme.

What l claim is: l. A combustion apparatus including, in combination: ahollow body defining a combustion chamber therein, said hollow bodyformed with an opening at one end thereof;

conduit means carried by said hollow body and communicating with saidopening for delivery of air into said chamber;

a fuel nozzle having a discharge end generally centrally disposed insaid conduit means for delivery ofa fuel spray to said conduit means andhence into said chamber, the discharge end of said nozzle being disposedupstream of thejunction of said conduit and said hollow body;

a closure member for restricting the flow of air through said conduit,said closure member extending between said nozzle discharge end and saidconduit and formed with a plurality of generally radially elongatedslots for passage of air therethrough;

said closure member being formed with a peripheral flange and a centralopening adapted to slidingly receive the discharge end of said fuelnozzle, said peripheral flange floatingly received within a peripheralgroove defined, at least in part, by said conduit whereby said closuremember is accurately located relative to said fuel spray andunrestricted relative movement may occur between said fuel nozzle, saidclosure member and said conduit during periods of thermal expansion ancontraction.

2. A combustion apparatus including, in combination:

a hollow body having a generally closed upstream end and defining anannular combustion chamber therein, said hollow body upstream end formedwith a plurality of angularly spaced openings;

a generally cylindrical conduit for each said opening, each said conduitconnected, in flow communication with its respective opening, to saidupstream end of said hollow body and extending upstream thereof;

a fuel nozzle for each said conduit, each fuel nozzle having a dischargeend generally centrally disposed in its respective conduit, in axialspaced relationship to said opening, for delivery ofa fuel spray intosaid conduit; and

a closure member extending between said discharge end of said fuelnozzle and the upstream end of said conduit and formed with an annulararray of generally axially extending slots sized to deliver at least 25percent of the air required for stoichiometric combustion of itsrespective fuel spray, each said slot defined, in part, by generallyparallel, radially extending sidewalls, whereby said air is delivered asa plurality of radially elongated discrete streams about said fuel spraywhich dissipate in a region of turbulent interaction to thereby promotemixing of the air and fuel in a manner producing low smoke combustion.

1. A combustion apparatus including, in combination: a hollow bodydefining a combustion chamber therein, said hollow body formed with anopening at one end thereof; conduit means carried by said hollow bodyand communicating with said opening for delivery of air into saidchamber; a fuel nozzle having a discharge end generally centrallydisposed in said conduit means for delivery of a fuel spray to saidconduit means and hence into said chamber, the discharge end of saidnozzle being disposed upstream of the junction of said conduit and saidhollow body; a closure member for restricting the flow of air throughsaid conduit, said closure member extending between said nozzledischarge end and said conduit and formed with a plurality of generallyradially elongated slots for passage of air therethrough; said closuremember being formed with a peripheral flange and a central openingadapted to slidingly receive the discharge end of said fuel nozzle, saidperipheral flange floatingly received within a peripheral groovedefined, at least in part, by said conduit whereby said closure memberis accurately located relative to said fuel spray and unrestrictedrelative movement may occur between said fuel nozzle, said closuremember and said conduit during periods of thermal expansion ancontraction.
 2. A combustion apparatus including, in combination: ahollow body having a generally closed upstream end and defining anannular combustion chamber therein, said hollow body upstream end formedwith a plurality of angularly spaced openings; a generally cylindricalconduit for each said opening, each said conduit connected, in flowcommunication with its respective opening, to said upstream end of saidhollow body and extending upstream thereof; a fuel nozzle for each saidconduit, each fuel nozzle having a discharge end generally centrallydisposed in its respective conduit, in axial spaced relationship to saidopening, for delivery of a fuel spray into said conduit; and a closuremember extending between said discharge end of said fuel nozzle and theupstream end of said conduit and formed with an annular array ofgenerally axially extending slots sized to deliver at least 25 percentof the air required for stoichiometric combustion of its respective fuelspray, each said slot defined, in part, by generally parallel, radiallyextending sidewalls, whereby said air is delivered as a plurality ofradially elongated discrete streams about said fuel spray whichdissipate in a region of turbulent interaction to thereby promote mixingof the air and fuel in a manner producing low smoke combustion.